Black Insomnia Coffee was launched in South Africa last year and following laboratory tests in Switzerland, has been confirmed as the strongest coffee in the world.

It's so strong one consumer information site has branded it the 'deadliest' and one cup offers DOUBLE the recommended dose for adults.

The brand was founded and launched by Sean Kristafor last June who first began selling locally to cafes in Cape Town. Now it's available worldwide by mail order - and it looks set for international success.

Formerly a brand called Death Wish Coffee claimed the World's Strongest Coffee crown, but the new lab tests confirm that Black Insomnia has 6.35 per cent MORE caffeine.

A 12 fl oz cup of Death Wish averages 660mg of caffeine but the same amount of Black Insomnia Coffee averages 702mg.

In the USA Fox News found Black Insomnia has three times the caffeine of a Tall Starbucks Pike Place, which has just 230mg.

"If you want to stand out, you need to be the 'best' — the biggest, smartest, strongest, or cheapest," Kristafor said about his robusta beaned product.

His coffee brand has been dubbed the “deadliest” of all by consumer information site Caffeine Informer knocking two competitors Death Wish Coffee and Wodfee (marketed as the 'world's strongest coffee blend with added caffeine')

Kristafor warns that it should be used with caution and only by people who have a high tolerance to caffeine should drink it. One cup offers double the recommended dose for adults.

He says Black Insomnia he had sourced special robusta beans that have the highest levels of caffeine.

In Switzerland, samples were tested via liquid chromatography - the separation of a mixture by passing it in a solution - and Black Insomnia has 17.5 grams of caffeine per kilogram of coffee.

By comparison, Death Wish Coffee was evaluated as having 13.2 grams per kilogram and WodFee had 13.8 grams. A dark roast from Starbucks has around 5 grams of caffeine per kilogram, approximately.

But the South African special has competition saying that “nine different brands on Amazon” alone that claim some version of the 'world's strongest'.

However founder Kristafor has an ace up his sleeve. He explained that they've actually reduced the amount of caffeine in their current drink prior to making it available for consumption.

Black Insomnia may have dangerously high levels of caffeine but the brand is already warning other coffees not to compete in an “attempt to surpass this content in the interest of public health and safety”.

The brew is available in 16-ounce bags online. In South Africa, a cold brew version and machine pods are available.